Threat Level: green Handler on Duty: Didier Stevens

SANS ISC: Extracting signatures from Apple .apps - SANS Internet Storm Center SANS ISC InfoSec Forums


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Extracting signatures from Apple .apps


As an add-on to ISC Handler Lenny Zeltser's earlier diary on extracting certificates from signed Windows binaries, here's how to do the same on a Mac. Given that today's blog over at F-Secure documents a screenshot-taking Mac spyware that is signed with a developer ID, signed bad .apps might actually be more prevalent than expected.

To verify and extract signatures and certificates on an Apple .app, you can do (example Mail.app)

codesign -dvvvv --extract-certificates  /Applications/Mail.app

This will save the certificates in DER format, named codesign0, codesign1, etc. These can then be displayed as usual with OpenSSL

openssl x509 -inform DER -in codesign0 -text

 

Daniel

367 Posts
ISC Handler

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